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Mt. St. Helens Eruption
Transcript of Mt. St. Helens Eruption
The most recent series of eruptions started back in 1980.
This tragic explosion created a large crater, and the series didn't end until six years later, after about a dozen extrusions of lava were injected into the massive crater. What happened? Before May 18, of 1980, more than 10,000 earthquakes were recorded in foreshadowing to the great explosion.
On the actual day, the earthquake before the eruption had a magnitude of 5.1 which caused the volcano's bulge and summit to slide away, creating a huge landslide.
The landslide depressurized the magma buildup creating severe explosions.
Rocks, ash, volcanic gas, and steam were blasted upward and to the north, traveling at about 300 miles per hour, causing some of the damage seen in ecosystems in the aftermath of the explosion. The entire ecosystem was affected, autotrophs like nearby forests were destroyed by mudflows, ash and lava. This caused the producers of Mount Saint Helens region to be destroyed, thus afflicting the foodwebs and depending tropic levels Effect on Autotrophs and Heterotrophs Heterotrophs, like plant consuming deer and other animals quickly died, if they hadn't already been killed by the initial disaster, because their food sources were unavailable due to deposits of ash. Effect on Carnivores, Herbivores, and Omnivores. The decreasing levels of herbivores had afflicted the carnivorous race as well, since their food source was diminishing. since the producers and herbivores were dying off, the omnivores of the ecosystem were affected as well. After the climax of the catastrophe, the decomposers had "kicked in," returning the overall environment to a relatively "new" state, thus allowing pioneer species of plants and producers to reclaim the area and the denizens and consumers of the forest had started to repopulate and thrive. Therefore, it had restored the food chains and food webs of the ecosystem. The Comeback of the Region Effects on Element Cycles A debris avalanche at the beginning of the eruption deposited 3 billion cubic yards of various material to the north fork toutle river. A new drainage system was formed on top of the avalanche, which created increased runoff to creeks and rivers. This led to higher frequency in floods because the river would overflow from the runoff water. Water Cycle Nitrogen Cycle Carbon Cycle The nitrogen cycle played an important role in controlling biogeochemical cycling because of the limited amount of nitrogen compounds. The process of nitrogen fixation was active but the process of nitrification was limited only to bacteria of aerobic characteristics. This caused for an abundance of nitrogen compounds in the free nitrogen bank because the atmospheric nitrogen was being converted into nitrates and when plant and animals die, decomposing bacteria send nitrogen back into the air through denitrification. When the volcano erupted, large amounts of volcanic gas, dust, and ash were deposited into the atmosphere. The gases contain high amounts of carbon dioxide. This could be an example of cumbustion because a significant amount of carbon dioxide is being released by an event where heat is involved. This provides an element in photosynthesis, plants use the carbon dioxide to produce glucose which will benefit soil, plant and animal respiration. There is also an abundance of carbon dioxide in the air due to the comounds also being submitted by decomposition and soil erosion. Symbiotic Relationships
after the Eruption Mutualism After the eruption, plants and fungi were involved in a mutualistic relationship called mycorrhiza. The fungi lived in the cortex cells of the plants' roots and helped the plants absorb inorganic nitrogen and phosphorous from the soil. Commensalism In the Pacific northwest, commensalistic relationships have been exhibited by opossums and woodchucks. This happens whenever the woodchucks leave their burrows and opossums soon take over it, claiming them as their own in order to raise their young. This doesn't effect the woodchuck, but it is beneficial towards the opossum. Parasitism The Armillaria Ostoyae, also known as the honey mushroom, can grow up as big as 1,666 football fields in area, and kills trees for their nourishment whilst growing. Succesion Primary Succesion occured in some places since the eruption, such as the newly developed pumice rock. Wind played a factor in transporting new seeds, spores, as well as insects and other living organisms to the area. Pioneer species include: prararie lupine, moss, lichens, and shrubs.
Secondary succesion occured in places that weren't affecte majorly by the explosion. These species also grew in the lava flow zone after the pioneer species managed to fertilize the soil. These species include silver firs and mountain hemlocks.
After these ecosystems had managed to grow to their full potential, they have become old growth forests, much like its surrounding areas. Preadtor-Prey Relationships These realtionships have developed throuhgout nature and has certainly not left out the Pacific Northwest region. An example of this type of relationship is shown between organism like phytoplankton, small fish, salmon, and bears.